| Abstrakt: |
The results of nearly 500 mechanical analyses on soils of the Oxford region are summarized, to define norms for the textures of soils on the main local parent materials. Surprisingly, the standard deviations of individual clay and silt analyses, about the means for soils on each parent material, bear very little relation to the apparent heterogeneity of the rocks. This probably indicates the prevalence of drift in a formerly periglacial area of mature and sub-mature relief. The older procedures for mechanical analyses consistently show lower clay, and higher silt and fine sand contents, than the International procedure, by about 15 per cent of the total soil. The coefficients of variation of individual results about the mean for each soil, pooled over all soils and both clay and silt fractions, are 40.6 per cent by the older procedure and 25.3 per cent by the International procedure. [ABSTRACT FROM AUTHOR] |
Plný text